09V/09VI (095/096) Nuclear Submarine Thread


tphuang

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That reactor uses fuel enriched to <5% and has a refuelling time of 2.5 years. That's completely unsuitable for a nuclear submarine.
That's because it's a civilian reactor used to generate electricity on a barge.

This one is intriguing to me because it's produced by Bohai shipyard and at a size/power generation that you could theoretically fit in to a nuclear submarine. Looking at this, it makes me wonder if China achieved a certain capability level in mini nuclear reactor technology to be able to put something like this in civilian market. Does this indicate they are now capable of building a 200 MW reactor for submarine?
 

SEAD

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Okay, let's not alarm anyone with the 2027 rumor. That's just to have the capability, but not to actually carry anything out. Keep in mind that strategic investments like carrier and nuclear subs help a Taiwan scenario but they are more for longer term strategic goals of securing SLOC for the future.

In 2000, PLAN SSN fleet consisted of 091s and 092, so it was more like early 1950s level. Keep in mind that when they first developed the submarine reactor for 091, it 2 decades before they connected their first domestic Qinshan nuclear reactor onto the grid. I would not dare to spend prolonged period of time next to a 091 reactor. the current PWR technology vs back in 2000 is night and day. If you just look at
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, the domestic nuclear reactor technology really only reached 2nd generation with CNP600 in 2010 and only reached 3rd generation with Hualong One in 2021.

I'm quite intrigued by this ACPR50S to be built by Bohai shipyard. Not saying this is what's going into Type 095. It certainly looks like something that can adopted for naval use.
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You can see that if they finalized on a nuclear submarine reactor design in 2011, they'd basically be using a reactor utilizes 2nd generation technology and then it will take another 3 years to launch the boat and 3 more years after that for it to join service. So if they have a modern reactor designed in 2020 with 200 MWt, then it probably won't be on a boat that's in service until 2027.
I’m not an expert so no comment for tech level, but I’m sure the development among ‘generations’ of civilian reactors is more about safety, less about economy and None about volume/power/noise. So it’s a little bit weird for me, just like analyzing LO capability of X-32 but your argument is the range of B-737…

On the other hand, I’m also sure the design of HEU reactor and LEU reactor are different so any similarity of size maybe just by chance. People around the world did a lot of work to transfer HEU reactors to civilian LEU civilian versions, so we do know it’s not easy.
 
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SEAD

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Also, we are not comparing spending money on "SSNs" with "additional MRBMs and/or bombers".
We are comparing spending money on "additional VLS tubes" with "additional and/or bombers".
I got it and can’t agree more. IMO it’s a waste to attack fixed sites in Guam by SSNs but anyway VLS is worth, perhaps the most worth investment.
 

FairAndUnbiased

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I would say that for reasons of economics and capability, Chinese SSNs should focus on things that only subs can do, and not on replicating capabilities that other platforms can do, just from underwater. That is because unlike ground forces, surface ships, aircraft and spacecraft, subs cannot communicate large bandwidth data in real time with other units. They can barely even send data at all, only receive.

Subs also have a hard time with long range targeting and self positioning. It is difficult to identify and precisely locate a ship with sonar from 100+ km out while it is trivial with radar or optical sensors.

Subs cannot receive either satellite or land based positioning signals continuously. To locate themselves they use inertial navigation which has compounding errors. They need a satellite comm beacon that surfaces (and is easily visible to aircraft) to communicate 2 way. To receive orders while submerged they can only rely on ELF signals with extremely low bandwidth.

That makes them unsuitable for a highly coordinated effort requiring cooperation with other forces in real time and with constant communication, like a conventional first strike on a highly defended military target in open water.

They're much more suitable for stealthy, low profile missions: short ranged ambushes, mine laying, underwater recon for fixed structures like cables and pipelines.

I'd say, focus on their core capabilities. Mine laying, UUV, torpedo, maybe some tube adapted missiles for flexibility, but no need for a huge VLS farm if it adds more than 20-30% cost.

As for what they can do in improvement to compensate for their weaknesses and focus on their strengths, it'll be things like deploying mines, UUV, submersibles, hydrophones or decoys (things that only subs can do), and long range torpedos utilizing lessons learned from UUV technology to passively propel themselves as far as possible towards a target until the final sprint.
 

SEAD

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I would say that for reasons of economics and capability, Chinese SSNs should focus on things that only subs can do, and not on replicating capabilities that other platforms can do, just from underwater. That is because unlike ground forces, surface ships, aircraft and spacecraft, subs cannot communicate large bandwidth data in real time with other units. They can barely even send data at all, only receive.

Subs also have a hard time with long range targeting and self positioning. It is difficult to identify and precisely locate a ship with sonar from 100+ km out while it is trivial with radar or optical sensors.

Subs cannot receive either satellite or land based positioning signals continuously. To locate themselves they use inertial navigation which has compounding errors. They need a satellite comm beacon that surfaces (and is easily visible to aircraft) to communicate 2 way. To receive orders while submerged they can only rely on ELF signals with extremely low bandwidth.

That makes them unsuitable for a highly coordinated effort requiring cooperation with other forces in real time and with constant communication, like a conventional first strike on a highly defended military target in open water.

They're much more suitable for stealthy, low profile missions: short ranged ambushes, mine laying, underwater recon for fixed structures like cables and pipelines.

I'd say, focus on their core capabilities. Mine laying, UUV, torpedo, maybe some tube adapted missiles for flexibility, but no need for a huge VLS farm if it adds more than 20-30% cost.

As for what they can do in improvement to compensate for their weaknesses and focus on their strengths, it'll be things like deploying mines, UUV, submersibles, hydrophones or decoys (things that only subs can do), and long range torpedos utilizing lessons learned from UUV technology to passively propel themselves as far as possible towards a target until the final sprint.
In 1993, GAO claimed the communication between headquarters and SSBNs is as fast/reliable as silos. So if they’re only used as launching platforms, communication is not a big deal. The difficult part is to leverage ISR capability of SSNs.
 
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tphuang

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I’m not an expert so no comment for tech level, but I’m sure the development among ‘generations’ of civilian reactors is more about safety, less about economy and None about volume/power/noise. So it’s a little bit weird for me, just like analyzing LO capability of X-32 but your argument is the range of B-737…

On the other hand, I’m also sure the design of HEU reactor and LEU reactor are different so any similarity of size maybe just by chance. People around the world did a lot of work to transfer HEU reactors to civilian LEU civilian versions, so we do know it’s not easy.
I was told that KLT40S is very similar to OK-650 reactors used by Akula and Borei class (and even the first Yasen I think). And in this case, ACPR50S seems to just be a more powerful/efficient thank KLT40S (35MWe/150MWt vs 50MWe/200MWt)

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The KLT-40 family of reactors has the same modular PWR design as Afrikantov’s OK-900 and OK-900A, but with a lower enrichment
(< 20% enriched) reactor core. The OK-900A has more than four decades of operational use in the propulsion systems of Russia’s six Arktika-class polar icebreakers, most of which have retired from service.

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OK-900A specifications:
  • Fuel: 90% enriched uranium in the form of
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    uranium-zirconium alloy fuel elements
  • Fuel load: 150.7 kg
  • Power production: 171 megawatts

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Check slide 25
OK-650 is believed to be a variant of OK900A PWR with support systems rearranged and modified to fit within the submarine hull
Kirov class uses KN-3, which uses an OK-900A variant capable of operating at significantly higher power.

Check slide 26, So both KLT40S and OK-650V have the sam lineage back to OK-900A.

So if China is capable of building a 200MWt ACPR50S, it would seem to me that building a 200+ MWt reactor for submarine should be a given at this point. Given the size of Akula and Yasen class, I think the next Chinese SSN will be huge.
 

SEAD

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I was told that KLT40S is very similar to OK-650 reactors used by Akula and Borei class (and even the first Yasen I think). And in this case, ACPR50S seems to just be a more powerful/efficient thank KLT40S (35MWe/150MWt vs 50MWe/200MWt)

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OK-900A specifications:


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Check slide 25
OK-650 is believed to be a variant of OK900A PWR with support systems rearranged and modified to fit within the submarine hull
Kirov class uses KN-3, which uses an OK-900A variant capable of operating at significantly higher power.

Check slide 26, So both KLT40S and OK-650V have the sam lineage back to OK-900A.

So if China is capable of building a 200MWt ACPR50S, it would seem to me that building a 200+ MWt reactor for submarine should be a given at this point. Given the size of Akula and Yasen class, I think the next Chinese SSN will be huge.
now there’s a trend to build small civilian reactors. there’re many plans around the world but rarely relevant to submarine reactors design. I prefer to treat KLT40S as a Cold War time exception.
 
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FairAndUnbiased

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In 1993, GAO claimed the communication between headquarters and SSBNs is as fast/reliable as silos. So if they’re only used as launching platforms, communication is not a big deal. The difficult part is to leverage ISR capability of SSNs.
By what mechanism? There's only a few known mechanisms by which to communicate underwater, they're all low bandwidth or short ranged. And communication with SSBNs is much simpler (command to launch at predetermined targets or to release beacon for 2 way comms) than that for SSNs.
 

SEAD

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By what mechanism? There's only a few known mechanisms by which to communicate underwater, they're all low bandwidth or short ranged.
We don’t know but ELF is enough to transmit a targeting location in <1min. Its bandwidth is around 1bps.
And communication with SSBNs is much simpler (command to launch at predetermined targets or to release beacon for 2 way comms) than that for SSNs.
SSBNs have the ability to retarget underwater by command.
 

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